# 4 Types of EAC formulas, when to use what

Submitted by pmp3456 on Mon, 10/04/2010 - 16:23

I see there are 4 types of EAC forecast calculation formulas available, but confused when to use each type.

EAC = BAC / CPI

EAC = ETC + AC

EAC = (BAC-EV) + AC

EAC = [BAC-EV / spi * cpi] + AC

Please need a brief justification / explanation.

Thank you all for the helpful info.

Forums:

javerose

Tue, 10/05/2010 - 21:14

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## Hi pmp3456EAC = BAC / CPI,

Hi pmp3456

EAC = BAC / CPI, assume project costs are going to continuo in the same rate

EAC = ETC + AC, initial estimates are flawed

EAC = (BAC-EV) + AC, there was one big issue impacting cost, but for the rest of the project typical behaviour is expected.

Last one, have no idea

AnuMahesh

Thu, 10/07/2010 - 14:53

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## EAC formulas and when to use

Per Rita's book,

EAC = AC + Bottom up ETC -- Used when original estimate is fundamentally flawed

EAC = BAC / Cumulative CPI - Used if no variances have occured and same rate of spending will continue

EAC = AC + (BAC- EV) - Used when variances are atypical /irregular

EAC = AC + ( BAC-EV / Cumulative CPI * Cumulative SPI) - Used when variances are typical(regular). Assumes poor cost performance. Hope this helps.

pmp3456

Tue, 10/05/2010 - 23:41

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## 4 Types of EAC formulas, when to use what

Thanks Javerose, But when do you use the following any ideas?

EAC = [BAC-EV/spi*cpi] + AC

raj9

Wed, 10/06/2010 - 00:47

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## last one

it is used when project schedule is factor impacting ETC effort. i.e. there is negative performance to date and project schedule dates must be met.

kiranu23

Tue, 10/12/2010 - 12:22

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## The explanation for the EAC

The explanation for the EAC formulae is excellently given by Harwinder in his blog

www.deeprfriedbrain.com

It should be easy to the apply the related formula when you go through them once.

Regards,

Kiran

faisal khan

Tue, 10/12/2010 - 17:14

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## it seems, the link is

it seems, the link is incorrect, pls provide the correct link.

thanks

azooz24

Wed, 10/13/2010 - 14:10

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## the link is

http://www.deepfriedbrain.com/Deep_Fried_Brain/Home.html

admin

Fri, 01/10/2014 - 03:41

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## Check already discussed

Check already discussed posts

http://pmzilla.com/help-need-using-correct-eac-cost-formulas

http://pmzilla.com/confused-diff-formulas-eac-and-etc

pmalik

Thu, 12/08/2016 - 20:02

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## EAC Formulas

You should read the following article. It provides complete explanation of EAC formulas along with an example.

Estimate At Completion – 5 EAC Formulas for PMP Exam